Here's a rather nice little pistol which came my way the other day. Its a 7.65mm Walther Model 4, second pattern - probably circa late 1917 or 1918.
The pistol has matching numbers to the frame and slide, these being the only parts which were ever numbered. In 1915, the German government gave Walther a contract to supply 250,000 of these pistols. Although rather small in calibre, they were much favoured by German officers over the much harder hitting Luger P08. Their simple design made them an ideal choice for trench warfare. They were straightforward to take apart, had few components, and were easy to keep clean.